Oxidative lightening agents are generally employed for lightening keratin-containing fibers. The comprised oxidizing agents, mostly at least hydrogen peroxide, act in this regard to destroy natural melanin dyes as well as synthetic dyes, when present in and on the keratinic fiber, thereby decolorizing the fiber. In order to lighten dark starting fibers the use of further oxidizing agents, especially per salts, such as per sulfates, is usually necessary.
In order to accelerate the reaction during the oxidative application, oxidative dyes mostly exhibit an alkaline pH value that is adjusted with alkalizing agents, such as alkanolamines, ammonia or inorganic bases. Although in this regard ammonia in particular affords good dyeing results, it also manifests disadvantages for the user due to its odor and irritation potential for skin and mucous membranes. Consequently, increased efforts have been made to develop efficient oxidative dyes that dispense with the use of ammonia.
Oxidative lightening agents usually consist of two or more components, whose mixture is sufficiently viscous to allow it to be comfortably applied onto hair without any dripping or running. In the case where per salts are used, these components are expediently in powder form. However, this brings additional challenges to such lightening agents. In particular, the production of the ready-for-use agents by blending powdered blonding salt components and often highly viscous, creamy or pasty alkalizer preparations and developer preparations is often laborious and laden with problems of uniform, intimate mixing. Therefore, in particular the agent has to be able to be easily and quickly mixable and easily applied so as to prevent inhomogeneities in the concentration of the ingredients during the application and thus to ensure a uniform and the least possible damaging lightening result.
Accordingly, at least one object of the present invention is to optimize methods with oxidative lightening agents, such that the abovementioned disadvantages can be overcome. In particular, it is intended to provide stable lightening agents free of unpleasant odors and which, if possible, should also be free of ammonia.
A known application form in the oxidative hair dye sector is the foam application that the consumer associates with uniform coloration results that are gentle to the hair fiber. However, a disadvantage of the foam application is the use of propellant gases typically employed to form the foam, because the ability to avoid the use of propellant gases has recently become more important.
Another problem associated with foam application is the stabilization of the foam. The consistency of foams is considered to be ideal when the dispensed product affords a solid, stable foam that leaves a supple feel and breaks down only slowly on the hair. It is frequently observed, however, that the applied foams possess little stability and rapidly collapse, leaving behind a low viscosity solution that drips. Having said that, it is also important that the foam nevertheless wets the hair well, so as enable a good lightening. The foam stability is negatively influenced in particular by the presence of larger amounts of salts.
Accordingly, another object of the present invention is furthermore to optimize methods for the use of oxidative lightening agents for the foam application without the use of propellant gases, such that the above cited disadvantages can be overcome. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.